﻿using System;
using System.Collections;
using System.Configuration;
using System.Data;
using System.Linq;
using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.HtmlControls;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Xml.Linq;
using System.Drawing;

namespace MyOA.UI
{
    public partial class ValiDateNumber : System.Web.UI.Page
    {
        protected void Page_Load(object sender, EventArgs e)
        {
            
                this.GenImg(this.GenCode(4));
            
        }

        //产生随机字符串
        private string GenCode(int num)
        {
            string[] source ={"0","1","2","3","4","5","6","7","8","9",
                         "A","B","C","D","E","F","G","H","I","J","K","L","M","N",
                       "O","P","Q","R","S","T","U","V","W","X","Y","Z","a","b","c","d"
                         ,"e","f","g","h","i","j","k","l","m","n","o","p","q","r","s","t","u","v","w","x","y","z"};
            string code = "";
            Random rd = new Random();
            for (int i = 0; i < num; i++)
            {
                code += source[rd.Next(0, source.Length)];
            }
            return code;
        }

        //生成图片
        private void GenImg(string code)
        {
            //产生随机RGB颜色
            Random random = new Random();
            int r = random.Next(0, 256);
            int g = random.Next(0, 256);
            int b = random.Next(0, 256);
            Bitmap myPalette = new Bitmap(60, 20);//定义一个画板

            Graphics gh = Graphics.FromImage(myPalette);//在画板上定义绘图的实例

            Rectangle rc = new Rectangle(0, 0, 60, 20);//定义一个矩形

            gh.FillRectangle(new SolidBrush(Color.FromArgb(r, g, b)), rc);//填充矩形
            gh.DrawString(code, new Font("宋体", 16), new SolidBrush(Color.White), rc);//在矩形内画出字符串

            myPalette.Save(Response.OutputStream, System.Drawing.Imaging.ImageFormat.Jpeg);//将图片显示出来

            Session["ValidateCode"] = code;//将字符串保存到Session中，以便需要时进行验证

            gh.Dispose();
            myPalette.Dispose();
        }
    }
}
